History & findings: A 46 year old female with C/O swelling over anterior aspect of left thigh. 3 months, no other complaints. O/E: ECOG-1, General examination- grossly normal, no comorbidities. L/E: Ill defined non-tender mass ~2*3 cms over anterior aspect of left thigh in lower aspect in cutaneous plane. MRI thigh: Well defined heterogenous signal intensity in anterior and lateral aspect of lower thigh in subcutaneous plane -2.3*1.5 cm. No e/o muscle or bony involvement or lymphadenopathy. Biopsy: HPE & IHC: suggestive of Dermatofibrosarcoma Protuberans. PAN CK, S100, DESMIN- negative. CD-34 positive.
Treatment: Patient underwent wide local excision with split skin graft. Post op HPE: Dermatofibrosarcoma, Size- 3*3 cms, Circumferential margins- free. Deep resected margin -0.5 cm away from tumor. In view of close margin, she received adjuvant RT to local post op site with a CTV magin of 2 cms -Dose- 60 Gy/30#/6 weeks. On follow up for 6 months, she is asymptomatic with no evidence recurrence on imaging.
Discussion: Dermatofibrosarcoma protuberans (DFSP) is a rare superficial tumor characterized by high rates of local recurrence and low risk of metastasis. DFSP occurs most commonly on the trunk and proximal extremities, affects all races, and often develops between the second and fifth decade of life. The tumor grows slowly, typically over years. Histologically, several variants of DFSP have been described and should be well characterized to avoid misdiagnosis with other tumors. These include pigmented (Bednar tumor), myxoid, myoid, granular cell, sclerotic, atrophic DFSP, giant cell fibroblastoma, and DFSP with fibrosarcomatous areas. Of all these variants, only the DFSP with fibrosarcomatous areas is high grade, with a higher rate of local recurrence and distant metastasis.
Conclusion: DFSP is the most common cutaneous sarcoma. It originates in the dermis and tends to infiltrate underlying structures, including muscles, tendons, fascia and bone. In our case, the tumor was confined to the skin and subcutaneous tissue, however, our patient underwent adjuvant radiotherapy due to closer deepresected margin and to avoid a possible relapse that would infiltrate deeper structures. Long-term follow-up is strongly recommended.